Article 22 of the Convention On The High Seas of 1958, states:
1. Except where acts of interference derive from powers conferred by treaty, a warship which encounters a foreign merchant ship on the high seas is not justified in boarding her unless there is reasonable ground for suspecting:
(a) That the ship is engaged in piracy; or
(b) That the ship is engaged in the slave trade; or
(c) That though flying a foreign flag or refusing to show its flag, the ship is, in reality, of the same nationality as the warship.
It goes on to state that the naval vessels of one nation can stop the ship of a foreign nation if that ship has violated any laws or regulations of the nation to which the naval vessel belongs if it is found in that nation’s territorial waters.
It is clear that in the case of the boarding and detention of the Iranian oil tanker Grace 1, registered in Panama, as many ships are, off the Spanish coast, near Gibraltar, that Britain had no legal right to order its marines to board the Iranian ship which was either in international waters as the Iranians claim or in Spanish waters near Gibraltar. It is in flagrant violation of the Convention on the High seas to which it is a party and which therefore is also a part of the domestic law of the United Kingdom.
The pretext offered by the British for this act of war against Iran, and Syria if their claim is to be believed that the oil was being delivered to Syria, in violation of a claimed European Union embargo against Syria, is manifestly bogus since the European Union has no legal right to impose "sanctions" or any type of embargo, or naval blockade against Syria or any other nation. That right remains in the sole jurisdiction of the United Nations Security Council which has not authorized any such blockade. The EU edicts against Syria are therefore illegal and in international law do not exist.
The EU itself claims to justify its illegal oil embargo of Syria on Security Council Resolution 2254, and the 2012 Geneva Communique, both of which have the objective of seeking a peaceful political solution in Syria and do not give any EU states individually or the EU as a whole, the right to impose sanctions or any other type of warfare on Syria nor the right to enforce them against other nations such as Iran. Therefore, the British had no justification whatsoever for their actions.
The question then becomes was this an act of piracy or an act of war and the answer is, act of war, for it is not considered piracy under the Convention if a naval vessel of one nation boards and seizes the ship of another nation. Piracy exists where the boarding is for private purposes by private individuals acting in their own interest.
Article 15 of the Convention states,
(1) Any illegal acts of violence, detention or any act of depredation, committed for private ends by the crew or the passengers of a private ship or a private aircraft, and directed:
(a) On the high seas, against another ship or aircraft, or against persons or property on board such ship or aircraft;
(b) Against a ship, aircraft, persons or property in a place outside the jurisdiction of any State;
So the British action cannot be called "piracy" in a legal sense, though the term does fit the sense of what they have done and the Iranians like to use the term in their protestations against the British action. It is instead an act of war against Iran by Britain and in reality by the United States of America since it was admitted by the Brtish government that the seizure was conducted on orders from Washington as the Iranian foreign minister, Mr. Zarif, stated on July 17th
"The UK by confiscating our ship is helping the US in imposing its illegal oil sanctions against Iran."
Spain’s acting foreign minister, Josep Borrell, said Gibraltar had seized Grace 1 in response to a request from the US to Britain. El Pais reported that Borrell, from the Socialist Party (PSOE) said the US intelligence implied that the supertanker was in British territorial waters. The Spanish have formally complained of a British incursion into Spanish waters, but in reality they went along with the illegal action and also cited the illegal EU oil embargo on Syria.
